Due to an epic fail on the part of the USPS (a total nightmare), a shipment of 7 day-old, straight run, RO chicks ended up actually being 3 chicks, which are now 2.5 weeks old and doing well. We were shooting to end up with 3-5 pullets and one cockerel, but with only 3 having survived, there is no chance of hitting that mark. The breeder we got them from still had chicks from the same hatch that ours came from, so the plan is to ship another 6 chicks in ~2 weeks. They'll all be ~4.5-5 weeks old at that point, so my question is whether or not integrating the two "flocks" of chicks has a potential for problems. We usually start "official" main flock integration around 4-5 weeks, but I don't know if we should stagger that with each group of chicks (the 3 we have are already getting informal, short, and supervised introductions now), or make sure the chicks are all cohesive first. I know they start their pecking orders young, but typically not particularly viciously (that we've observed) like the adults can get. Still, we've never had to merge two groups of chicks before, so any input or advice is much appreciated.